engleski

The sinergetic effect of temperature and salinity on rotifer Brachionus plicatilis O.F.Mueller lorica size in mass rearing

Rotifer Brachionus plicatilis is commonly used organism as larval live food in marine finfish rearing. It has been shown that the prey size is function of larva's mouth size (Arthur, 1976 ; Beyer, 1980), and as it grows, it selects prey to meet its mouth opening (Hunter, 1980). We examined sinergetic effect of temperature and salinity on lorica size of mass cultured rotifers. For the experiment rotifers were inoculated in three tanks with 400 l of medium, with ceramic heaters and custom made aeration system (Skaramuca, 1994). Rotifers were fed microalga Nannochloropsis sp. with cell density at 4x106cellsml-1ą1x106cellsml-1. We reared rotifers at nine combinations of 38, 27 and 20psu and 35, 27 and 22°C for five days to allow the rotifers to acclimatizate to conditions, and during the day 6 to day 10 we performed daily measurements of lorica length and width on 50 animals per set of conditions. The numbers were subjected to ANOVA statistical analysis (P<0.05). ANOVA (F=46.757, P<0.001) showed significant difference between rotifers reared at different salinities and temperatures. The loricas of rotifers reared at 38psu and 27°C had the lowest average value, with 89.50% of individuals smaller than 150mm. That differed significantly from any other combination (<0.001). The highest average lorica lengths were noted at 20psu and 22°C, with 53.87% of individuals in range 150-250mm. As a rule, the highest percentages(<50%) of rotifers smaller than 150mm were found in tanks with 38psu. The highest number (58.43%) of rotifers in range of 150-250mm were found on 27psu, 22°C. Fukusho and Iwamoto (1980) contribute this phenomena to seasonal cyclomorphosis, while Hirano (1987) is of opinion that difference in size is due to the higher reproduction rate of rotifers at higher temperatures. Genetical makeup and other factors, such as metabolism and adaptive physiology are also stated as causes of differences in size. While we have been dealing with S-type of Brachionus plicatilis, we yielded signifficantly different rotifers, which implies that optimal combination of temperature and salinity are required in rearing rotifers of specific size.

sinergetic efect ; Brachionus plicatilis

https://www.researchgate.net/profile/Pero_Tutman/publication/294448391_The_sinergetic_effect_of_temperature_and_salinity_on_Rotifer_Branchionus_plicatilits_O_F_MULLER_population_growth_and_lorica_size_in_mass_rearing/links/580f4dbe08aea04bbcba3360/The-sinergetic-effect-of-temperature-and-salinity-on-Rotifer-Branchionus-plicatilits-O-F-MUeLLER-population-growth-and-lorica-size-in-mass-rearing.pdf